As sensor elements to be used for magnetic direction sensors or the like, magneto-impedance sensor elements using magnetic amorphous wires whose properties change according to an external magnetic field (hereinafter, “MI sensor elements”) has been developed (see Patent Document 1).
Such an MI sensor element has a base body composed of a nonmagnetic body, a magnetic amorphous wire held onto the base body, a coating insulator through which the magnetic amorphous wire passes, and a detecting coil formed around the coating insulator.
Since the MI sensor element having such a constitution is mounted to portable terminal devices such as cellular phones, size-reduction of the MI sensor element is demanded according to size-reduction and thickness-reduction of such devices.    Patent Document 1: International Publication No. 2005/008268